1. Field of the Invention
The present invention relates to internal combustion engines.
An internal combustion engine system can be subdivided into a number of inter-related sub-systems which operate together to bring about a desired performance in relation to speed, power output, fuel consumption and exhaust emission of the engine system. These subdivisions are:
(a) ignition means PA1 (b) management of fuel input PA1 (c) management of gas flow inside the engine cylinders and combustion chamber PA1 (d) segregation mechanisms PA1 (e) mixing of fuel and air in a combustion chamber PA1 (i) The engine compression ratio can be chosen without regard to the fuel used since spontaneous ignition by compression can be prevented, PA1 (ii) at partial load, the fuel input can be reduced without a deliberate reduction in air input. This results in an "ultra lean burn" operation of the engine, PA1 (iii) at partial load there is also no need for any mechanical interference with the airflow during induction of the air, as is effected, for example, by a throttle valve which leads t pumping losses. PA1 first means for delivering a charge of substantially air into said first cylinder; PA1 second means for delivering a charge of liquid fuel into said second cylinder; PA1 respective first and second pistons movable in said cylinders; PA1 continually operable ignition means in said combustion chamber; PA1 control means for controlling said second means to commence delivery of said charge of fuel into said second cylinder during movement of said second piston between a first position wherein said piston is at the commencement of its induction stroke and a second position wherein said piston is not less than 10.degree. angle of movement from the end of its compression stroke and to terminate delivery of said charge of fuel when said second piston reaches a third position no later than the inner dead centre position of the piston at the end of the compression stroke; and PA1 means for inhibiting movement of fuel/air mixture from said second cylinder into said combustion chamber prior to said second piston reaching a fourth position wherein said piston has completed at least substantially 80% of its compression stroke length and means for inducing a vortex motion in air delivered to said combustion chamber from said first cylinder for assisting rapid mixing in said combustion chamber of fuel/air mixture from said second cylinder and air from said first cylinder during combustion. PA1 first means for delivering a charge of substantially air to said first cylinder; PA1 second means for delivering a charge of liquid fuel into said second cylinder; PA1 respective first and second pistons movable in said cylinders; PA1 control means for controlling said second means to commence delivery of said charge of fuel into said second cylinder during movement of said second piston between a first position wherein said piston is at the commencement of its induction stroke and a second position wherein said piston is not less than 10.degree. angle of movement from the end of its compression stroke and to terminate delivery of said charge of fuel when said second piston reaches a third position no later than the inner dead centre position of the piston at the end of the compression stroke; and PA1 means for inhibiting movement of fuel/air mixture from said second cylinder into said combustion chamber prior to said second piston reaching a fourth position wherein said piston has completed substantially 80% of its compression stroke length and means for inducing a vortex motion in air delivered to said combustion chamber from said first cylinder for assisting rapid mixing in said combustion chamber of fuel/air mixture from said second cylinder and air from said first cylinder during combustion. PA1 (a) a combination of a large swept volume cylinder containing air only (or air with such a small quantity of fuel as to render it unignitable by the ignition means in the combustion chamber, the upper limit of any such fuel/air mixture ratio being below the lower (lean) flammability limit for such a mixture) with a smaller swept volume cylinder into which the fuel is introduced. The two cylinders are interconnected by a common combustion chamber. PA1 (b) The introduction of fuel into the smaller cylinder in liquid form cools the gases in the smaller cylinder by evaporation, so lowering the pressure there in relation to the pressure in the larger cylinder at any given piston positions during the compression stroke up to a final part of the compression stroke. This effectively promotes a flow of gas from the larger cylinder through the combustion chamber to the smaller cylinder. PA1 (c) An optional feature is that the phase difference between the positions of the pistons in the larger and smaller cylinders can be chosen to set the crank angle at which the contents of the smaller cylinder enter the combustion chamber to initiate the ignition and combustion process. PA1 (d) The combustion chamber communicates with the smaller cylinder by way of an aperture which restricts the flow of gas into the smaller cylinder during the induction stroke, thus affecting the pressure in the smaller cylinder at the commencement of the compression stroke in order to retain the pressure there at a lower value than the pressure in the larger cylinder.
The diesel engine system, in addition, also has the following sub-systems:
Segregation is the term used to describe the exclusion of fuel from the combustion chamber of the engine during the induction and compression strokes of the engine to prevent premature ignition when a continually operable ignition means is situated in the combustion chamber. Segregation confers a considerable fuel efficiency benefit on an internal combustion engine for the following reasons:
2. Description of the Prior Art
The diesel engine is the only internal combustion engine currently available which uses segregation in its operation. During operation, air is drawn into a cylinder of the engine and is compressed to a high volume ratio (14:1 to 25:1) as a result of which the air is heated to a high temperature of between 300.degree. C. and 400.degree. C. Fuel is not injected into the cylinder until the end of the compression stroke. Because of the high temperature of the air, the fuel ignites spontaneously. However, combustion does not take place immediately the fuel is injected. The fuel enters the cylinder in the form of liquid droplets. These must mix intimately with the air in the cylinder and vaporise before they can ignite to commence combustion. This inherent delay in combustion renders the combustion process a relatively slow process which limits the efficient operation of the diesel engine to relatively low speeds. The segregation referred to above is effected mechanically in the diesel engine by the fuel injection pump the injector needle of which mechanically segregates the fuel from the cylinder or combustion chamber until the moment of injection.
The present invention seeks to provide an improved internal combustion engine.